Removal Behavior of Surface Modified Sand for Cd(II) and Cr(VI) from Aqueous Solutions

Sand which is a good filter medium and widely used in wastewater treatments possesses a very insignificant sorption capacity for several heavy metal toxic ions. However, surface-modified sand as impregnated with manganese is supposed to possess fair removal capacity at least for the low level removal of several heavy metal toxic ions from aqueous solutions since manganese is likely to be aggregated onto the sand surface as manganese dioxide which is a good adsorbing material. The present investigation intends to exploit the use of sand obtained from the river Tlawng, Sairang site, Aizawl, Mizoram, India. The sand sample was impregnated with Mn(II) by a wet method. Further, the surface morphology of this manganese-impregnated sand (MIS) was obtained using scanning electron microscopy, which showed that the manganese oxide occupied the surface of the sand and clustered on it. The particle size of coated manganese oxide was found to be in the nanoscale range. Moreover, the specific surface area of the sand was also increased with this impregnation. Further, the removal efficiency of MIS was assessed for two important heavy metal toxic ions, that is, Cr(VI) and Cd(II). The study was carried out for the pH and concentration dependence of sorptive solutions. Results obtained for the concentration dependence were further analyzed by the Freundlich and Langmuir adsorption isotherms.